Lightweight alloys
Discussion
For a hypothetical Audi S4 biturbo track car prokject...
I understand the basic principles of reducing unsprung weight but how pronounced is the effect to average/amateur track drivers?
As I say, it's hypothetical, some mates and I have been toying with building a track car project after our elise was inadvertently written off
Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?
I understand the basic principles of reducing unsprung weight but how pronounced is the effect to average/amateur track drivers?
As I say, it's hypothetical, some mates and I have been toying with building a track car project after our elise was inadvertently written off
Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?jollygreen said:
For a hypothetical Audi S4 biturbo track car prokject...
I understand the basic principles of reducing unsprung weight but how pronounced is the effect to average/amateur track drivers?
As I say, it's hypothetical, some mates and I have been toying with building a track car project after our elise was inadvertently written off Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?
There is a rule of thumb that a kilo taken off a wheel is equivalent to a reduction of five kilos of sprung weight. If anything, I'd say that is an understatement.I understand the basic principles of reducing unsprung weight but how pronounced is the effect to average/amateur track drivers?
As I say, it's hypothetical, some mates and I have been toying with building a track car project after our elise was inadvertently written off
Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?Reducing weight of wheels will improve grip, acceleration, and braking and make the steering lighter and more precise.
You will definitely notice a difference of three kilos/wheel, and perhaps two or even less.
Image wheels in Tipton or Compomnotive in wolverhampton and look at their respective split rims. i use image billet centre alloys, very light though not exactly dirt cheap.
if you are looking to cheap wheel/tyre weight down, its worth looking at tyre weights too. road car carcass tyres are soooo much heavier than slicks for instance due to the carcass reduction. depending on tyre size possibly 2-3kg per tyre. also wheel tyre diameter. a lot of mod prod style cars go away from 17-19" wheels in favour of samller rolling radius 15 or even 13" wheels/tyres. lowers the car, reduces rolling radius and weight. genreally shortens gearing why may be an advantage depending on the discipline to intend to compete in. No point in having 170mph gearing on most UK circuits, but blistering acceleration is another matter.
if you are looking to cheap wheel/tyre weight down, its worth looking at tyre weights too. road car carcass tyres are soooo much heavier than slicks for instance due to the carcass reduction. depending on tyre size possibly 2-3kg per tyre. also wheel tyre diameter. a lot of mod prod style cars go away from 17-19" wheels in favour of samller rolling radius 15 or even 13" wheels/tyres. lowers the car, reduces rolling radius and weight. genreally shortens gearing why may be an advantage depending on the discipline to intend to compete in. No point in having 170mph gearing on most UK circuits, but blistering acceleration is another matter.
Also try Team Dynamics and Speedline for wheels, they both make some fairly lightweight ones. If you've got a large wallet, look at some of the respected Japanese manufacturers too (Volk Racing, Desmonds etc) as they make some real featherweights too and generally in a vast range of fitments.
Keep in mind that you are not obliged to run a wheel that has been formally approved (such as by the TuV) for road use. The tests to which such road wheels are put are way OTT.
As CNH says, there are big differences in the weights of tyres as well. Rather unlike the situation with wheels, however, in a tyre lighter is not necessarily better. The stiffness of the sidewall, hinge and belt will have a dramatic effect on handling.
I would always choose a tyre regardless of its weight, rather than because of it, whilst the weight of the wheel would be a primary criterion.
As CNH says, there are big differences in the weights of tyres as well. Rather unlike the situation with wheels, however, in a tyre lighter is not necessarily better. The stiffness of the sidewall, hinge and belt will have a dramatic effect on handling.
I would always choose a tyre regardless of its weight, rather than because of it, whilst the weight of the wheel would be a primary criterion.
Another thing: recall that all weight is not created equal. The farther out from centre the weight is, the worse it is.
If you're looking at a wheel with a heavy central section but optimal spokes/rim, that would be better than a wheel of the same weight but which is overbuilt out towards the rim.
Another consideration is that if you get lightweight wheels, you'll want to make sure that your tyrefitter knows what he is doing. It is far from impossible for an inattentive fitter to crack a somewhat delicate rim.
If you're looking at a wheel with a heavy central section but optimal spokes/rim, that would be better than a wheel of the same weight but which is overbuilt out towards the rim.
Another consideration is that if you get lightweight wheels, you'll want to make sure that your tyrefitter knows what he is doing. It is far from impossible for an inattentive fitter to crack a somewhat delicate rim.
The Japanese manufacturers are the kings of the lightweights, just have a gander at the likes of the produce from Works, Rays, Gram Light, Weds, etc etc. Proper 3 piece split rims with rolled outer rims will always (or should) be lighter than cast or forging & the weight is less at the outside diamter. BBS is another go for the RS ones or the Le Mans ones 
Here's some for you to drool over
BBS Le Mans - but go for gold
Here's some for you to drool over
BBS Le Mans - but go for gold
Edited by cptsideways on Tuesday 4th March 23:23
Declan,
You have not followed my link above.
I'm afraid the Jap's still haven't got out of the traps when it comes to weight
http://www.dymag.com/index2_e.html
Phil
79 De Tomaso Longchamp GTS
You have not followed my link above.
I'm afraid the Jap's still haven't got out of the traps when it comes to weight
http://www.dymag.com/index2_e.html
Phil
79 De Tomaso Longchamp GTS
Dymag do a great job, but wise to recall that a carbon wheel will not deform, it will only shatter.
That is not a big problem on a racing car, where you go round and round repeating the the same trace, the road surface is well-maintained without random potholes, the driver is covered with and surrounded by safety equipment, there is a marshal every one hundred metres, and if you do go off it usually is into a gravel trap or safety barrier, rather than into a tree or into the path of an oncoming lorry or people carrier filled with children.
That is not a big problem on a racing car, where you go round and round repeating the the same trace, the road surface is well-maintained without random potholes, the driver is covered with and surrounded by safety equipment, there is a marshal every one hundred metres, and if you do go off it usually is into a gravel trap or safety barrier, rather than into a tree or into the path of an oncoming lorry or people carrier filled with children.
Ford developed 'plastic' wheels at one time for the granadas, but found whilst they could be abused far beyond alloys, they would continue to 'look' and drive OK, but actually be damaged and waiting to fail, so never went into production.
as Flemke said, big diameter wheels however light in design, struggle to match smaller diameter wheels and tyres in terms of weight. as for my suggestion re lighter tyres, slicks, wets and Avon ACB10s for instance (List 1B road legal-ish) are much lighter and stiffer carcasses than a road tyre, so does depend on your particular use for the project car. bigger wheels and tyres often spoil the ride and the handling, so dont necessarily think that bigger is better (well with wheels/tyres at least)
www.imagewheels.co.uk/
http://www.comp.co.uk/wheels/modular.asp
as Flemke said, big diameter wheels however light in design, struggle to match smaller diameter wheels and tyres in terms of weight. as for my suggestion re lighter tyres, slicks, wets and Avon ACB10s for instance (List 1B road legal-ish) are much lighter and stiffer carcasses than a road tyre, so does depend on your particular use for the project car. bigger wheels and tyres often spoil the ride and the handling, so dont necessarily think that bigger is better (well with wheels/tyres at least
)www.imagewheels.co.uk/
http://www.comp.co.uk/wheels/modular.asp
leorest said:
flemke said:
cptsideways said:
flemke said:
It does indeed. I'm not sure how happy I'd be running something like that. Even if the centre is meant to be covered with a hubcap to conceal the ugliness, the structural integrity of the layout surely leaves something to be desired.
Agreed. It's obviously done to save on production/inventory costs rather than benefit the customer. leorest said:
flemke said:
It does indeed. I'm not sure how happy I'd be running something like that. Even if the centre is meant to be covered with a hubcap to conceal the ugliness, the structural integrity of the layout surely leaves something to be desired.
Agreed. It's obviously done to save on production/inventory costs rather than benefit the customer. flemke said:
leorest said:
flemke said:
It does indeed. I'm not sure how happy I'd be running something like that. Even if the centre is meant to be covered with a hubcap to conceal the ugliness, the structural integrity of the layout surely leaves something to be desired.
Agreed. It's obviously done to save on production/inventory costs rather than benefit the customer. jollygreen said:
For a hypothetical Audi S4 biturbo track car prokject...
Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?
1) Yes, it is. I am trying to learn car setup on a Porsche (or some would say, Volkswagen/Audi) 924S, which has KW v3 adjustable coil overs. This is quite stiff for my car, as it has been designed for the heavier 944/968. Light wheels take a lot of "stiffness" out of the feel of the car, so that you get the benefit of little lean/roll, but the light wheels mean fewer jolts. I'm using early 911 Fuchs wheels, which are forged, and about as light as possible, at 5 Kg for 15". The same car with 7.7Kg 16" feels clumsy on street. On track, grip rules, and the difference is much less pronounced.Is it a worthwhile change to make after suspension/brakes/engine/cage etc have all been done?
2) As you can see, don't discount old wheels. Not sure what PCD/offset/size you're after, but e.g. Fuchs wheels are still about as good as you can get strength/performance wise. Wheels are one area where most of the development seems to have been to make things visually more attractive, rather than lighter & stronger.
Gassing Station | Suspension, Brakes & Tyres | Top of Page | What's New | My Stuff